"Here's the official guidance, my sources say: Anything currently/formerly known as a 'Metro-Style application' (with or without a hyphen) will now be known officially as a 'Windows 8 application'. References to the 'Metro user interface' will now be replaced by "Windows 8 user interface." And instead of saying 'Metro design', the Softies and those adhering to their official guidelines will be using the words 'Windows 8 design'." Microsoft not being allowed to use the Metro name here is just as ridiculous as Apple trolling Samsung. All ridiculous exponents of the western world's IP fetish.

I think I also heared that applications for ARM aren't source compatible with x86/amd64 and vice versa. If that is true that would be really stupid.

Partly true. The short version is that for ARM, they've ditched various legacy APIs. So if an app is coded as a Metro app, it'll run on everything - but if it's coded in the classic Windows APIs, it's not going to work on ARM.